The State of the Art of "Nanometer-Scale Fabrication" has been given with an excellent bibliography, as of 1982 [1]; wherein, it is stated on p.3:
" . . . electron, ion and X-ray exposure, . . . limitations of the resist . . . not those of the exposure system . . . set the ultimate limit on . . . resolution"; and: "The most commonly used resist for high resolution (&lt;100 nm or 1000 A) is (PMMA) polymethylmethacrylate. A resolution of &lt;50 nm. or 500 A may be obtained with other resists . . . not well studied. "; and: "exposure of PMMA with a high intensity 50 kV field-emission electron beam source with a 20 nm. beam of 10.sup.-7 amps . . . takes 1 day (86,400 sec.) to expose a dense pattern on a 4" square (100 cm..sup.2 or 10.sup.-2 m.sup.2), with additional time for stage motion and alignment."
This is a speed of about 10.sup.-7 m.sup.2 /sec; and a resolution of only 500 A.
The use of reactive ion etching to produce locallized probes 1000 A apart is reported [2] but this resolution is also not small enough, and there is no increase in speed.
For the manufacture of Lepcon.TM., Elcon.TM. and such devices this speed is too small; and the resolution not small enough. A speed of about 0.1 m.sup.2 /sec and a resolution of 10 A is required, not obtainable with these prior art devices.
A 10 A resolution is reported [3]:
"Using a 1/2 nm (5 A) diam beam of 100 keV electron, we have etched lines, holes and patterns in NaCl crystals at the 2 nm. (20 A) scale size. Troughs about 1.5 nm. wide on 4.5 nm centers and 2 nm dia holes have been etched completely through NaCl crystals more the 30 nm thick." and "The scanning transmission electron microscope (VG Microscopes, Ltd., Model HB5) in operation in the National Research and Resource Facility for Submicron Structures at Cornell University can produce up to 1 nA of 100 keV electrons in a beam dia as small as 1/2 nm (5 A). This beam current density of 1/2.times.10.sup.6 A/cm.sup.2 means that it takes only 10 .mu.s to deposit a dose of 5 coulombs/cm.sup.2 in the sample." and "Two types of materials . . . alkali halides and aliphatic amino acids . . . can easily be vacuum sublimated or evaporated as uniform thin films . . . readily vaporized by electron beams. Using 100 keV electrons a dose of about 10.sup.-3 C/cm.sup.2 is sufficient to etch through 30 nm of L-glycine, while a dose of 10.sup.2 C/cm.sup.2 is needed to etch through a similar thickness of NaCl."
In the latter reference the resolution is satisfactory but the speed is too slow.
Recently (1986) there has been a report on a new X-Ray lithography device [4]. This article stated:
Submicron lithography using storage ring Xray sources may be closer . . . volume production . . . 1990's. A compact synchroton storage ring will be mated with a vertical stepper . . . will produce 12 A wavelength at 630 MeV energy level . . . When mTED TO THE COSY storage ring, the XRS should have a resolution of 0.2 .mu.m (2000 A) . . . alignment accuracy to within 0.1 .mu.m (1000 A). The stepper will expose wafers up to 8 in. (0.2 m) dia.
A Field-Emission Scanning Transmission Microscope (STEM), shown in FIG. 8, has been described [5,8]. A field emitter is employed to produce an emission area having a diameter of 30-300 A. One magnetic lens with a short focal length and low spherical aberration, is used to demagnify this source to a resolution of 2 to 5 A on the specimen surface. The field emission gun and lens is mounted in an ultrahigh vacuum vessel that operates at 10.sup.-8 to 10.sup.-7 Pa. When a short focal length lens is utilized to keep the system compact, aberration may be compensated by a "stigmator".
In these Prior Art Devices the speed is too slow for the rapid production of devices for the Lepcon.TM.-Elcon.TM. Technology described in the copending applications hereinabove specified.